Maximizing Feed Flow and Preheat

One of the best means of stabilizing the operation of a distillation column is to hold both the feed flow and feed temperature constant. If feed flow variations are unavoidable, the impact of these disturbances can be reduced by feedforward correction of the reflux flow (material balance). If the reflux flow is modified in the right proportion (m) and at the right time, the consequences of feed flow variations can be minimized. 

In cases where both the demand for the product and the availability of feedstock are unlimited, increasing the throughput of the column maximizes profitability. In such installations a valve position controller can be 

The vapor recompression system uses recovered heat (left). The pressure of such a distillation process can be controlled by modulating the speed of the compressor or the bypass around it (right). 

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